I am using Boost unordered_map. I have a key value pair for each entry. How could I determine whether a particular value exist in the map? (I don't want to create another unordered_map which stored the value as key and key as value)

Little kids don't want a trip to the dentist, but good parenting does it anyway.
– chrisaycockDec 9 '10 at 5:25

1

@ephemient: I think the OP doesn't want to have to maintain a separate data structure (more likely). Therefore if it comes all packaged, I can't see why there would be an issue (since the equality is defined anyway for value).
– Matthieu M.Dec 9 '10 at 10:46

Description:
Count elements with a specific key
Searches the container for elements whose key is k and returns the number of elements found. Because unordered_map containers do not allow for duplicate keys, this means that the function actually returns 1 if an element with that key exists in the container, and zero otherwise.